When the dust settles: Field experiments measure how everyday activity resuspends hazardous particles

Being prepared for an emergency is key to keeping people safe. This means more than just having supplies such as food, water and first-aid kits. Sometimes, the most important preparation is having the right data to help first responders and the community stay safe.

Researchers at the U.S. Department of Energy’s Argonne National Laboratory are helping fill the information gap on how dangerous dust particles from a radiological event may be resuspended in the air and spread. A radiological event occurs when radioactive material is released into the environment.

Through field experiments, Argonne researchers studied the resuspension, or movement, of dust particles from concrete surfaces during a simulated radiological contamination scenario. They measured how people walking and cars driving affected the spread of the particles. The research has been published in Health Physics.

Focusing on safety: Why accurate particle resuspension estimates matter

The resuspension of hazardous particles from the ground poses significant risks during chemical, radiological and biological contamination scenarios. Once the particles are kicked back up into the air, they can be inhaled. This raises the risk of exposure and complicates cleanup efforts.

Accurate modeling of resuspension helps develop contamination control strategies, guide emergency response and keep people safe.

Older computer models underestimate the number of particles picked up into the air because of people and vehicle activity. The models do not accurately predict resuspension factors. A resuspension factor is the amount of dangerous material in the air compared with the amount on the ground.

“We started to recognize that the radiation exposure models didn’t handle the dust that is thrown back up in the air very well,” said Mike Kaminski, Argonne senior nuclear chemical engineer and co-author of the paper. “There wasn’t any guidance on how to run that part of the model correctly, so we started looking into it.”

Putting it to the test: Four experimental scenarios

To fill these gaps, the researchers conducted first-of-a-kind field experiments. They measured resuspension factors for activities that would likely happen during an emergency response.

“This is the only study that has quantitatively measured dust on concrete in this way,” Kaminski said. “Almost all of the data we have was collected from nuclear weapon detonation experiments in the desert early on during the Cold War and within uranium and plutonium nuclear facilities.”

The four scenarios were walking, marching, vacuuming and driving a vehicle. All experiments used Arizona Test Dust (ATD), which acts like contaminated environmental dust. Particle detectors measured how much dust was kicked up.

To replicate how people move, such as pedestrians or first responders, the researchers set up a long tent and walked and marched through the dust. Marching was included because it simulates the fast movements of emergency workers or an evacuation scenario.

The data showed that casual walking produced low resuspension factors, which matched the results of earlier studies. Marching significantly increased resuspension.

The vacuuming experiments simulated a street sweeper or someone vacuuming at home. Vacuuming mainly resuspended smaller particles.

For the vehicle experiment, the team used a patch of road on Argonne’s campus. They spread ATD on the road and drove over it at different speeds with a sport utility vehicle (SUV). They measured both when the tires passed over the dust and when the bottom of the vehicle passed over it.

The vehicle tests showed that driving an SUV over dusted pavement produced substantial resuspension, especially of larger particles.

Filling the gap: How the data will improve emergency response

Few researchers have studied how people and vehicles affect resuspension factors.

“Previous studies on people’s movements exclusively focused on indoor activity and surfaces such as carpeting and hardwood flooring. Vehicle resuspension studies were looking primarily at everyday air quality,” Kaminski said.

Modelers could not accurately assess risks and help make informed decisions on emergency response safety with the data available. This study fills the gap.

The results show that resuspension during emergency operations is significantly higher than many models had predicted. Argonne’s data now provides previously unknown resuspension rates to experts around the world.

This new data will help improve many parts of emergency response. It will help inform contamination control and improve decisions on protective gear and emergency response strategies, such as evacuation or shelter-in-place protocols. Now, when emergency crews prepare for a radiological event, they will have not only the tools but also the accurate resuspension data they need to keep responders and the public safe.

Who’s behind this story?

Sadie Harley

BSc Life Sciences & Ecology. Microbiology lab background with pharmaceutical news experience in oil, gas, and renewable industries.

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Robert Egan

Bachelor’s in mathematical biology, Master’s in creative writing. Well-traveled with unique perspectives on science and language.

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